2G Misfiring! *Reward*

[gma0408]

First of all, I would like to say that I have been searching and reading up on anything that might help me fix my problem. I've been working (on and off) trying to solve this for the last 3 months!

So it's come to this: If someone helps me find or leads me to the solution of my misfiring, I'll either pay them or give them a part off of my car...cop, new 1G TB, etc. I haven't really decided yet.

If you guys can't solve it, I'm taking it to a shop. You guys are my last resort.


It all started when I drove my car home...in the rain...if that means anything. The car ran like a champ up until i got to the garage. It started misfiring....throughout the entire rpm. Well up until about 4k, because it'll bog if I try to take it higher. The exhaust smells like the car is putting out too much gas. When I try and drive the car, it jerks....its the same feeling it had when my positive battery connector was loose a while back.

I do have DSMlink, but I'm not really familiar with it yet. I just got the car up and running this spring after having done a 6 bolt swap.

The car is showing no cels.

Things that I have changed out....

-cam angle sensor
-COP...for stock coils and wires
-Power Transistor
-Spark plugs... new bpr7es with the correct gap
-ECU...tested in a friends car
-2 relays behind radio
-Gold box ...MFI relay?
-GM MAF
-Map sensor

Things that I have checked...

-boost leaks...slight one at bov, but fixed it and no change
-timing
-Compression is perfect...motor is nearly new
-grounds...cleaned up ALL connections/terminals
-injectors...new, but checked anyway
-battery...new, but checked
-Alternator... putting out 13.9 volts
-Fuel pump is working and fuel regulator gauge shows constant pressure
-ISC..coils are good
-Undid turbo timer and boost controller

The only things I have not changed out yet are the MAF Translator...which when unplugged the car will actually idle better, the injector resistor pack on the firewall, and the engine harness.

PLEASE HELP! Any ideas or thoughts would be appreciated.

 

[gma0408]

I don't have an AF guage. The lean reading i'm getting is coming from dsmlink. That comes from the o2 sensor and other things that your suppose to put in for dsmlink to calculate it...like fp/ what size injectors, etc.

 

[gma0408]

Ok, I installed the 2g maf....and NOTHING. It's still runs the same way.

I did get code 1500 and 1300...which I fixed and cleared.

I really thought I had the answer. The car did idled fairly well when the maf is not connected to the intake pipe....just like when I unplugged the translator.

SO, am I screwed? I really did change out every part that could possibly go bad....Other than the wire harness, which will probably be the next and last thing done.

God help me.

I'm tempted to just part the car instead of taking it to a shop. First for sale, a 2g maf.

 

[grnchevyz]

hmm, just reading this again...did you ever change the Front O2 sensor? Even if it shows .2 to .9 reading it could be faulty once warmed up. just wondering because it was one suggestion and don't see if you changed it or not...

Let us know.

 

[TerminalTalon]

Do a vacuum test. You might have cracked a vacuum line or blown something loose. Just throwing that out there. Your MAF sees so much air, dumps gas but does not get that air. I know this because every once in a while after running low boost I get pissed off at someone a run high. 22PSI. And subsequently blow my elblow of to my TB. Did it today messing with a first class in my squadron in a 3.0 Z3.

 

[92awddsm]

I think you guys are missing that the car went from functioning properly to exhibiting this problem without any changes to the engine.

If he just got it up and running this spring and has been trying to figure this problem out for 3 months(May, which is spring here), that means that it wasnt functioning properly to begin with. From what I gathered from his posts, he made it from the shop(evidently where the work was done) to home. The shop could have been 1/2 mile away, we dont know because he hasnt told us. Its not like it was running fine for the past year and now all of a sudden just started running poorly. And there was changes to the engine, he went from a 7 bolt to a 6 bolt.

 

[92awddsm]

Was the 255 pump installed at the same time all the other work was done? If so, I would also pull the pump and check the o-ring seal where it mounts to the pickup assembly. I have seen too many times that the o-ring on the pump either rips or cocks sideways not allowing a good seal to the pickup. In this situation, you could have good fuel pressure but fuel volume needed for higher rpms just isnt there.

 

[slipstream808]

Sorry, every once in a while I forget that not everyone has this ability (it's an ECU+ capability).

No, Don, he can do that with DSMLink. Logging MAFRaw shows you the Hz reading as it is going into the ECU. MafComp logs the Maf signal in Hz as offset by the airflow sliders. MafSD (simulated data) allows you to log Maf Hz as adjusted by the volumetric efficiency table. Logging Maf allows you to see the Maf Hz that is actually being used to calculate airflow, whether it be adjusted or not.

Now this is for EVERYONE:

DSMLink's calculated AFR is based on airflow, injector size, deadtime compensation, specific gravity of the fuel, and injector duty cycle. It is by no means at all related to the o2 sensor. The o2 sensor log is only good for seeing if it's working, or whether you are flooring it, decelerating, or cruising.

So PLEASE post me a log. I would like to see:

MAFRaw
MAFComp
MAF
Airflow/Rev
Airflow (in lbs/min)
IDC
Injector on time
TPS
Speed
RPM's
Idle switch
STFT
LTFTlo
LTFTmid
SelectLTFT

Thanks!!

 

[donmagicjuan]

Thanks for the DSMlink lesson, Tyler. It's always interesting to hear about the differences between the various tuning devices. I didn't realize this whole time we weren't talking about O2 voltages.

 

[slipstream808]

^^^ Oh, no problem! I've had it for a while and have played around with it a lot.

 

[gma0408]

The thing about the car is that I bought it with a 7 bolt that had bad rings. After about a year of aquiring parts/ upgrading I had it running in February.

It had been running perfectly( with no changes to the setup) up until about July...which is less than 3 months, but it sure does seem that long.

So, today Ill check the fuel pump o ring and log onto dsmlink again and get those readings

I also noticed when I reconnected my Apexi turbo timer, that the 02 volts is only reading 0.02 to 0.08....and doesn't fluctuate. I'm not really sure if that signifies anything or if it's even correct. The TT is connected to the wire going to the ecu though.

I should probably check the sensor with the multimeter directly, but what points/wires on the 02 plug do I check with the multimeter?

When I switch over to the A/F option it shows around 15:1, but most of the time it doesn't even show up? It flashes a couple of dashes.

Another thing to note,

cel P1300 means ignition adjustment circuit malfunction.

I really don't know what that means and it's the first time I've seen it.

I also played around with the cam angle sensor and when i retard it all the way(counter clockwise) the car is a lot smoother....like when I didn't have my translator or 2g maf plugged in.

 

[92awddsm]

The thing about the car is that I bought it with a 7 bolt that had bad rings. After about a year of aquiring parts/ upgrading I had it running in February.

It had been running perfectly( with no changes to the setup) up until about July...which is less than 3 months, but it sure does seem that long.

So, today Ill check the fuel pump o ring and log onto dsmlink again and get those readings

I also noticed when I reconnected my Apexi turbo timer, that the 02 volts is only reading 0.02 to 0.08....and doesn't fluctuate. I'm not really sure if that signifies anything or if it's even correct. The TT is connected to the wire going to the ecu though.

I should probably check the sensor with the multimeter directly, but what points/wires on the 02 plug do I check with the multimeter?

When I switch over to the A/F option it shows around 15:1, but most of the time it doesn't even show up? It flashes a couple of dashes.

Another thing to note,

cel P1300 means ignition adjustment circuit malfunction.

I really don't know what that means and it's the first time I've seen it.

I also played around with the cam angle sensor and when i retard it all the way(counter clockwise) the car is a lot smoother....like when I didn't have my translator or 2g maf plugged in.

When the 1g cas was wired in, did you solder the connections or use butt connectors? With the p1300 code, sudden change in performance, and better running with the timing retarded, it would lead me to believe that you have a poor connection in the wiring or the intake cam jumped timing by 1 or 2 teeth. You said you rechecked cam timing and it was good so I would recheck the connections for the cas.

And I apologize to donmagicjuan for what I quoted you on. According to the original post from gma0408, he made it sound as if he had just gotten the car running with the 6 bolt and the problem started when he got it home. If it had been running fine since Feb, that should have been stated in the original post. He said he had just gotten it up and running this spring after the 6 bolt swap(not feb) and has been chasing this problem for 3 months(this spring) so I instantly assumed that it was a fresh swap with typical arising problems that occur when you do that many mods at one time.

 

[gma0408]

When the 1g cas was wired in, did you solder the connections or use butt connectors? With the p1300 code, sudden change in performance, and better running with the timing retarded, it would lead me to believe that you have a poor connection in the wiring or the intake cam jumped timing by 1 or 2 teeth. You said you rechecked cam timing and it was good so I would recheck the connections for the cas.

And I apologize to donmagicjuan for what I quoted you on. According to the original post from gma0408, he made it sound as if he had just gotten the car running with the 6 bolt and the problem started when he got it home. If it had been running fine since Feb, that should have been stated in the original post. He said he had just gotten it up and running this spring after the 6 bolt swap(not feb) and has been chasing this problem for 3 months(this spring) so I instantly assumed that it was a fresh swap with typical arising problems that occur when you do that many mods at one time.

Sorry. I should of made that clear.

I check the wiring of the cas as well.

 

[donmagicjuan]

And I apologize to donmagicjuan for what I quoted you on.

Bah, don't sweat it! I think my assumption that DSMlink AFRs come from O2 voltages trumps that anyway.